contrib/fuzz/dirstate_corpus.py

stream-clone: disable gc for the initial section for the v3 format

The number of small container created turn Python in a gc-frenzy that seriously
impact performance.

This significantly boost performance. The following number comes from a large
private repository using perf::stream-locked-section:

base-line:   35.04 seconds
prev-change: 24.51 seconds (-30%)
prev-change: 20.88 seconds (-40%)
this-change: 14.22 seconds (-60% from baseline; -31% from prev)

import argparse
import os
import zipfile

ap = argparse.ArgumentParser()
ap.add_argument("out", metavar="some.zip", type=str, nargs=1)
args = ap.parse_args()

reporoot = os.path.normpath(os.path.join(os.path.dirname(__file__), '..', '..'))
dirstate = os.path.join(reporoot, '.hg', 'dirstate')

with zipfile.ZipFile(args.out[0], "w", zipfile.ZIP_STORED) as zf:
    if os.path.exists(dirstate):
        with open(dirstate, 'rb') as f:
            zf.writestr("dirstate", f.read())